Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P32/00—Diffusion of dopants within, into or out of wafers, substrates or parts of devices
  • H10P32/10—Diffusion of dopants within, into or out of semiconductor bodies or layers
  • H10P32/16—Diffusion of dopants within, into or out of semiconductor bodies or layers between a solid phase and a liquid phase
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
  • C09D129/02—Homopolymers or copolymers of unsaturated alcohols
  • C09D129/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/06—Silicon
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/08—Germanium
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
  • C30B31/04—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion materials in the liquid state
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
  • H10D62/60—Impurity distributions or concentrations
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/121—The active layers comprising only Group IV materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P32/00—Diffusion of dopants within, into or out of wafers, substrates or parts of devices
  • H10P32/10—Diffusion of dopants within, into or out of semiconductor bodies or layers
  • H10P32/14—Diffusion of dopants within, into or out of semiconductor bodies or layers within a single semiconductor body or layer in a solid phase; between different semiconductor bodies or layers, both in a solid phase
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P32/00—Diffusion of dopants within, into or out of wafers, substrates or parts of devices
  • H10P32/10—Diffusion of dopants within, into or out of semiconductor bodies or layers
  • H10P32/19—Diffusion sources
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/32—Phosphorus-containing compounds
  • C08K2003/329—Phosphorus containing acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/32—Phosphorus-containing compounds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/547—Monocrystalline silicon PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a coating liquid for impurity diffusion which is applied onto a semiconductor substrate to form an impurity diffusion layer on the substrate, and more specifically, to a coating liquid for impurity diffusion suitable for applying by screen printing.
• the coating liquid for impurity diffusion described in JP-A-2007-53353 or JP-A-2007-35719 comprising a phosphorus compound or a boron compound as an impurity, a water-soluble polymer such as a polyvinyl alcohol, and water, has a specific range of viscosity, and is capable of forming a uniform film on a semiconductor substrate by the screen printing method.
• the film is thereafter heat-treated to form an impurity diffusion layer, and a semiconductor having a reduced variation in resistance is achieved.
• a method including a coating liquid applying step followed by an etching step, or a method including a mask pattern forming step followed by a coating liquid applying step is conventionally employed for the pattern formation.
• the screen printing method using the coating liquid for diffusion described in JP-A-2007-53353 and JP-A-2007-35719 is capable of performing pattern printing, thereby obviating the aforementioned steps. Therefore, the screen printing method is highly useful for the production of the solar cells.
• the coating liquid for diffusion used for screen printing typically contains an organic solvent miscible with water in order to control the drying speed and the fluidity of the film, which helps improve the leveling property of the film.
• the polyvinyl alcohol in the coating liquid has a lower solubility in the organic solvent. Therefore, the each coating liquid is liable to increase its viscosity with time or suffer from precipitation of insoluble substances depending on the composition thereof and the conditions when used. Where the screen printing is continuously carried out or resumed after an idle period, printing failure or incomplete pattern is liable to occur due to the clogging of a screen mesh.
• a coating liquid for impurity diffusion which comprises: (A) a polyvinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (1) (the polyvinyl alcohol is hereinafter referred to as "PVA”) : wherein R 1 , R 2 and R 3 each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R 4 , R 5 and R 6 each independently represent a hydrogen atom or an organic group; (B) an impurity; and (C) water.
• PVA polyvinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (1)
• R 1 , R 2 and R 3 each independently represent a hydrogen atom or an organic group
• X represents a single bond or a bond chain
• R 4 , R 5 and R 6 each independently represent a hydrogen atom or an organic group
• B an impurity
• C water
• the present invention has a main feature such that, in the coating liquid for impurity diffusion comprising the PVA resin, the impurity (a phosphorus compound or a boron compound), and water, the PVA resin has the specific structural unit having the 1,2-diol structure on its side chain.
• the inventive coating liquid for impurity diffusion is highly stable. Where the coating liquid for impurity diffusion is used for screen printing, therefore, the printing can be continuously carried out for a longer period of time or can be resumed after an idle period. Particularly in the pattern printing of the solar cells, the coating liquid for impurity diffusion ensures higher printing accuracy for a longer period of time. Thus, the coating liquid for impurity diffusion is industrially very useful.
• the inventive coating liquid for impurity diffusion comprises:
• the PVA resin used for the coating liquid for impurity diffusion has the structural unit represented by the following general formula (1): wherein R 1 , R 2 and R 3 each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R 4 , R 5 and R 6 each independently represent a hydrogen atom or an organic group.
• R 1 to R 3 and R 4 to R 6 are all hydrogen atoms, and X is a single bond. That is, a PVA resin having a structural unit represented by the following general formula (1') is preferably used:
• R 1 to R 3 and R 4 to R 6 may each be an organic group, which may be present in an amount that does not significantly impair the properties of the resin.
• the organic group include C 1 to C 4 alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and a tert-butyl group.
• These organic groups may have a functional group such as a halogen group, a hydroxyl group, an ester group, a carboxyl group or a sulfonic acid group as required.
• X is most preferably a single bond, which helps ensure thermal stability and stability under higher temperature or acidic conditions, but may be a bond chain as long as the effects of the present invention are not impaired.
• the bond chain include hydrocarbon chains such as alkylenes, alkenylenes, alkynylenes, phenylene and naphthylene (which may be substituted with a halogen such as fluorine, chlorine or bromine), and -O-, -(CH 2 O) m -, -(OCH 2 ) m -, -(CH 2 O) m CH 2 -, -CO-, -COCO-, -CO(CH 2 ) m CO-, -CO(C 6 H 4 )CO-, -S-, -CS-, -SO-, -SO 2 -, -NR-, -CONR-, -NRCO-, -CSNR-, -NRCS-, -NR
• a method of producing the PVA resin used in the present invention is not particularly limited, but examples of the production method preferably used include: (i) a method in which a copolymer of a vinyl ester monomer and a compound represented by the following general formula (2) is saponified; (ii) a method in which a copolymer of a vinyl ester monomer and a compound represented by the following general formula (3) is saponified and decarbonated; and (iii) a method in which a copolymer of a vinyl ester monomer and a compound represented by the following general formula (4) is saponified and deketalized.
• 3,4-diacetoxy-1-butene described above can be produced by synthesis through an epoxybutene derivative or by a reaction by which 1,4-diacetoxy-1-butene, an intermediate product obtained during production of 1,4-butanediol, is isomerized with a metal catalyst such as palladium chloride, as described, for example, in WO00/24702 , USP5,623,086 , USP6,072,079 or the like.
• a metal catalyst such as palladium chloride
• a carbonate ring or an acetal ring is liable to remain on its side chain if the decarbonation or the deacetalization is insufficient. Therefore, the PVA resin is liable to be crosslinked by the ring group to generate a gelatinous substance in a thermal drying step of a production process.
• the average polymerization degree of the PVA resin (A) is typically 100 to 4000, particularly 200 to 2000, preferably 300 to 1500 (as measured in conformity with JIS K6726).
• the resulting coating liquid is liable to have a lower viscosity, which makes it difficult to properly carry out the screen printing. Furthermore, the resulting film is liable to become thinner with an insufficient impurity. If the average polymerization degree is too high, on the other hand, the resulting coating liquid is not suitable for the screen printing, and therefore, is likely to cause a printing failure.
• the proportion of the 1,2-diol structural unit contained in the PVA resin (A) is typically 0.5 to 30 mol%, particularly 1 to 20 mol%, preferably 3 to 15 mol%. If the proportion is too low, it is impossible to achieve the effect of the use of the PVA resin (A) containing the 1,2-diol structural unit. If the proportion is too high, the drying property is likely to deteriorate, thereby the productivity is reduced.
• the proportion of the 1,2-diol structural unit in the PVA resin (A) can be determined based on 1 H-NMR spectrum of a fully saponified product of the PVA resin (with DMSO-d6 as a solvent and tetramethylsilane as an internal standard), more specifically, based on the peak areas attributable to hydroxyl protons, methine protons and methylene protons in the 1,2-diol unit, methylene protons in the main chain, and protons of hydroxyl groups connected to the main chain.
• the PVA resin (A) used in the present invention may be a single type of PVA resin or a mixture of two or more types of PVA resins.
• a mixture of the PVA resin (A) and an unmodified PVA or a modified PVA resin other than the aforementioned PVA resin (A) may be used.
• the averages of the polymerization degrees, the saponification degrees and the proportions of the 1,2-diol structural unit preferably fall within the aforementioned ranges.
• the resulting coating liquid is liable to have a lower viscosity, which makes it difficult to stabilize the film forming. If the proportion of the PVA resin (A) is too great, on the other hand, the resulting coating liquid is liable to have a higher viscosity, which results in deteriorating coating efficiency and clogging a screen mesh in the screen printing.
• Examples of the impurity (B) usable include a compound of a Group 13 element and a compound of a Group 15 element, which may be used either alone or in combination.
• the Group 15 element compound is generally used as an impurity for production of an N-type semiconductor, and examples thereof include a phosphorus compound and an antimony compound. Particularly, the phosphorus compound is preferably used. Specific examples of the phosphorus compound include phosphoric acids such as phosphoric anhydride (P 2 O 5 ) and phosphoric acid (H 3 PO 4 ), salts of phosphoric acids such as melamine phosphate and ammonium phosphate, and esters of phosphoric acids such as acid phosphoxy methacrylate, 3-chloro-2-acid phosphoxyethyl methacrylate, acid phosphoxy polyethylene glycol monomethacrylate and acid phosphoxy polyoxypropylene glycol monomethacrylate and salts thereof, and phosphorus chloride, among which water-soluble phosphorus compounds are preferably used and the phosphoric acids are particularly preferably used.
• phosphoric acids such as phosphoric anhydride (P 2 O 5 ) and phosphoric acid (H 3 PO
• the proportion of the Group 15 element compound in the coating liquid for impurity diffusion is typically in a range of 0.1 to 30 wt%, particularly 0.1 to 10 wt%, particularly preferably 0.1 to 5 wt%.
• the proportion of the Group 15 element compound is too small, the content of the Group 15 element (phosphorus or the like) in the impurity diffusion layer is liable to be reduced, which makes it impossible to provide a sufficient resistance. If the proportion of the Group 15 element compound is too great, the solubility of the PVA resin (A) is liable to be insufficient.
• the Group 13 element compound is typically used as an impurity.
• the Group 13 element compound include a boron compound and an aluminum compound.
• the boron compound is preferably used.
• Specific examples of the boron compound include boric acid, boric anhydride, boron trifluoride, boron trichloride, boron tribromide, boron triiodide, trimethyl borate, boron nitride, ammonium tetraborate (hydrate), alkyl borate ester, melamine borate and 9-BBN, among which water-soluble boron compounds are preferably used and boric acid and boric anhydride are particularly preferably used.
• boron compounds may be used either alone or in combination.
• the proportion of the Group 13 element compound in the coating liquid for impurity diffusion is typically in a range of 0.1 to 30 wt%, particularly 0.1 to 10 wt%, particularly preferably 0.1 to 5 wt%.
• the proportion of the Group 13 element compound is too small, the content of the Group 13 element (boron or the like) in the impurity diffusion layer is liable to be reduced, which makes it impossible to provide a sufficient resistance. If the proportion of the Group 13 element compound is too great, the solubility of the PVA resin (A) is liable to be insufficient.
• the proportion of the water (C) in the coating liquid for impurity diffusion is typically in a range of 20 to 85 wt%, particularly 30 to 80 wt%, particularly preferably 40 to 75 wt%. If the proportion of the water (C) is too small, the viscosity of the resulting coating liquid is liable to be excessively increased, which results in deteriorating coating efficiency and the clogging a screen mesh in the screen printing. If the proportion of the water (C) is too great, the viscosity of the resulting coating liquid is liable to be excessively reduced, which makes it difficult to stabilize the film forming, or causes the impurity content of the impurity diffusion layer to become excessively small.
• An alcohol (D) is preferably further blended in the coating liquid for impurity diffusion.
• D is preferably further blended in the coating liquid for impurity diffusion.
• an alcohol having a boiling point higher than water i.e., having a boiling point of 100°C or higher, more preferably 150°C to 350°C, particularly preferably 200°C to 300°C, because such an alcohol suppresses rapid drying of the film after printing and has more excellent effect on improving a leveling property.
• the proportion of the alcohol (D) blended in the coating liquid for impurity diffusion is typically in a range of 5 to 70 parts by weight, particularly 10 to 60 parts by weight, particularly preferably 30 to 50 parts by weight, based on the overall amount of the coating liquid.
• the proportion of the alcohol (D) per 100 parts by weight of the water (C) is typically in a range of 5 to 200 parts by weight, particularly 20 to 150 parts by weight, further preferably 80 to 120 parts by weight. If the proportion of the alcohol (D) is too small, it is impossible to sufficiently achieve the effect on improving the fluidity and the leveling effect. If the proportion of the alcohol (D) is too great, on the other hand, the solubility of the PVA resin (A) deteriorates, which makes it impossible to provide a homogeneous coating liquid. Where an alcohol with a higher-boiling point is used, an excessively great proportion of the alcohol (D) is not preferred because the coating liquid is required to be dried at a higher temperature for a longer period of time.
• hydrocarbon surfactants particularly acetylene glycol derivatives, are preferably used because the hydrocarbon surfactants prevent the inventive coating liquid from foaming and are excellent in defoaming property.
• An acetylene glycol derivative represented by the following formula (5) is preferably used: wherein R 12 and R 15 each independently represent a C 1 to C 20 alkyl group, particularly a C 1 to C 5 alkyl group, particularly preferably a C 3 to C 5 alkyl group; R 13 and R 14 each independently represent a C 1 to C 3 alkyl group, particularly preferably a methyl group; and R 12 and R 15 , and R 13 and R 14 , which may be the same or different, preferably have the same structure.
• n and m each represent an integer of 0 to 30, and particularly m + n is 1 to 10, particularly 1 to 5, and particularly preferably 1 to 3.
• the ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyn-4,7-diol is preferably used, in which the number (m + n) of added ethylene oxide units is preferably 1 to 2.
• the proportion of the surfactant (E) to be blended in the coating liquid for impurity diffusion is typically in a range of 0.1 to 10 wt%, particularly 0.3 to 8 wt%, particularly preferably 0.5 to 5 wt%, in the coating liquid. If the proportion of the surfactant (E) is too small, the foaming suppressing effect and the defoaming effect are liable to be insufficient. If the proportion of the surfactant (E) is too great, on the other hand, the surfactant is liable to be separated from the liquid, which makes it impossible to provide a homogeneous solution.
• Various types of inorganic particles may be blended in the coating liquid for impurity diffusion in order to improve the screen printing properties.
• examples of the inorganic particles include silica materials such as colloidal silica, amorphous silica, fumed silica, among which the colloidal silica is preferably used.
• the proportion of the inorganic particles in the coating liquid is typically in a range of 0.5 to 20 wt%, particularly preferably 1 to 10 wt%.
• the inventive coating liquid for impurity diffusion contains the PVA resin (A), the impurity (B) and the water (C) described above, and as required, the alcohol (D), the surfactant (E) and the other additives.
• the concentration and the viscosity of the coating liquid are too low, it is difficult to stabilize the film forming. Furthermore, the content of phosphorus, boron or the like in the resulting impurity diffusion layer is liable to be insufficient. If the viscosity of the coating liquid is too high, on the other hand, the coating efficiency is liable to be deteriorated. Furthermore, the screen mesh is liable to be clogged in the screen printing.
• the coating liquid for impurity diffusion is prepared by dissolving the PVA resin (A) and the impurity (B) described above in the water (C), and as required, blending the alcohol (D), the surfactant (E) and the inorganic particles (F) in the resulting solution.
• the methods for preparing the coating liquid include, but not limited to, a method comprising the steps of preparing the PVA resin (A) in the form of an aqueous solution and then blending the impurity (B) and the other additives with the aqueous solution, and a method comprising the steps of preliminarily mixing the PVA resin (A) and the impurity (B) together, adding the water (C) to the resulting mixture, dissolving the mixture in the water (C) with stirring and heating, and then adding the other additives to the resulting solution.
• the inventive coating liquid for impurity diffusion thus prepared is excellent in storage stability and, therefore, can be prepared and stored in bulk or divided into smaller quantities for delivery, or can be partly used with the rest thereof stored.
• the semiconductor is produced by means of forming an impurity diffusion layer of phosphorus, boron and such therein, with a method comprising the steps of applying the coating liquid for impurity diffusion onto a semiconductor substrate of such as silicon or germanium, drying, burning and diffusing the coating liquid.
• a known method is used for applying the coating liquid for impurity diffusion onto the semiconductor substrate.
• the method include a screen printing method, a gravure printing method, a relief printing method, a lithographic printing method, a spin coater method, a comma coater method, a die head coater method, and a die lip coater method.
• the inventive coating liquid is most effective for use in the screen printing method, and is capable of forming a homogeneous film on a large-scale wafer having a size of 4 inches or greater.
• the amount of the coating liquid applied onto the semiconductor substrate varies depending on the type of the substrate, the use purpose of the semiconductor, the amount of the impurity (a phosphorus compound, a boron compound or the like) contained in the coating liquid, a desired phosphorus or boron content, and the like, but typically in a range of 1 to 100 g/m 2 , particularly 1 to 50 g/m 2 .
• the applying step and the drying step may be sequentially performed.
• the burning step and the diffusion step may be performed as a single step. If the diffusion proceeds and a desired resistance is achieved in the burning step, the diffusion step may be obviated.
• the surface resistance of the semiconductor can be controlled by the impurity content, the diffusion temperature, the diffusion period and the like.
• the surface resistance is typically controlled at a level suitable for the use purpose in a range of 0.03 to 10000 ⁇ / ⁇ .
• a reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer was charged with 1500 parts of vinyl acetate, 800 parts of methanol and 240 parts of 3,4-diacetoxy-1-butene, and then 0.05 mol% of azobisisobutyronitrile (per the amount of the vinyl acetate) was added.
• the resulting mixture was heated in nitrogen stream with stirring, whereby polymerization was started.
• the polymerization rate of vinyl acetate reached 87%, m-dinitrobenzene was added to the resulting mixture to end the polymerization.
• unreacted vinyl acetate monomers were expelled outside the system by blowing methanol vapor into the system, whereby a methanol solution of a copolymer was prepared.
• the methanol solution was further diluted to a concentration of 40% with methanol, and the resulting methanol solution was places into a kneader. While the temperature of the solution was kept at 40°C, a 2% methanol solution of sodium hydroxide was added to the methanol solution of the copolymer in a proportion of 8 mmol per 1 mol of the total of the vinyl acetate structural unit and the 3,4-diacetoxy-1-butene structural unit in the copolymer to initiate saponification. During the saponification, a saponification product was precipitated into particles. The particles were filtered out, thoroughly washed with methanol, and dried in a hot air drier. Thus, an intended PVA resin (A1) was produced.
• the saponification degree of the PVA resin (A2) thus produced was 99.6 mol% as determined by an analysis of an alkali consumption required for the hydrolysis of the remaining vinyl acetate and 3,4-diacetoxy-1-butene.
• the average polymerization degree was 470 as determined by an analysis performed in conformity with JIS K6726.
• the proportion of the 1,2-diol structural unit represented by the general formula (1) was 12 mol% (see Table 1) as determined based on an integration value obtained through measurement of 1 H-NMR (300 MHz proton NMR using a DMSO-d6 solution and using tetramethylsilane as an internal standard at 50°C).
• a reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer was charged with 1000 parts of vinyl acetate, 400 parts of methanol and 120 parts of 3,4-diacetoxy-1-butene, and then 0.06 mol% of azobisisobutyronitrile (per the amount of the vinyl acetate) was added.
• the resulting mixture was heated in nitrogen stream with stirring, whereby polymerization was started.
• the polymerization rate of vinyl acetate reached 80%, m-dinitrobenzene was added to the resulting mixture to end the polymerization.
• unreacted vinyl acetate monomers were expelled outside the system by blowing methanol vapor into the system, whereby a methanol solution of a copolymer was prepared.
• the methanol solution was further diluted to a concentration of 30% with methanol, and the resulting methanol solution was placed into a kneader. While the temperature of the solution was kept at 35°C, a 2% methanol solution of sodium hydroxide was added to the methanol solution of the copolymer in a proportion of 8 mmol per 1 mol of the total of the vinyl acetate structural unit and the 3,4-diacetoxy-1-butene structural unit in the copolymer to initiate saponification. During the saponification, a saponification product was precipitated into particles. The particles were filtered out, thoroughly washed with methanol, and dried in a hot air drier. Thus, an intended PVA resin (A3) was produced.
• A3 an intended PVA resin
• the saponification degree of the PVA resin (A3) thus produced was 99.7 mol% as determined by an analysis of an alkali consumption required for the hydrolysis of the remaining vinyl acetate and 3,4-diacetoxy-1-butene.
• the average polymerization degree was 1200 as determined by an analysis performed in conformity with JIS K6726.
• the proportion of the 1,2-diol structural unit represented by the general formula (1) was 6 mol% (see Table 1) as determined based on an integration value obtained through measurement of 1 H-NMR (300 MHz proton NMR using a DMSO-d6 solution and using tetramethylsilane as an internal standard at 50°C).
• the semiconductor substrate After the semiconductor substrate, on which the phosphorus diffusion coating liquid was screen-printed as described above, was dried at 150°C for two minutes in a hot air circulation drier, the semiconductor substrate was put in a muffle furnace at 900°C, maintained for 15 minutes, and taken out. Then, the substrate was shaken and cleaned in a 46% hydrogen fluoride aqueous solution. Thus, a semiconductor including a phosphorus diffusion layer formed in the semiconductor substrate was produced.
• the surface resistance of the center of the resulting semiconductor with a 30-mm square pattern was measured by means of a resistance meter (LORESTAR with a PSP probe available from Mitsubishi Analytech Co., Ltd.) The results are shown in Table 3.
• a coating liquid for phosphorus diffusion was prepared in substantially the same manner as in Example 1, except that the PVA resin (A2) produced in Example of the Production Process 2 was used as the PVA resin (A) and the respective components were blended in proportions as shown in Table 2.
• the coating liquid for phosphorus diffusion was evaluated in the same manner as in Example 1. The viscosity of the coating liquid is shown in Table 2, and the evaluation results are shown in Table 3.
• a semiconductor was produced in substantially the same manner as Example 1 with the coating liquid, and evaluated in the same manner. The results are shown in Table 3.
• a coating liquid for phosphorus diffusion was prepared in substantially the same manner as in Example 1, except that the PVA resin (A3) produced in Example of the Production Process 3, diphosphorus pentaoxide and methyl carbitol were used as the PVA resin (A), the phosphorus compound (B) and the alcohol (D), respectively, and the surfactant (E) was not blended, and that the respective components were blended in proportions as shown in Table 2.
• the coating liquid for phosphorus diffusion was evaluated in the same manner as in Example 1. The viscosity of the coating liquid is shown in Table 2, and the evaluation results are shown in Table 3.
• a coating liquid for phosphorus diffusion was prepared in substantially the same manner as in Example 1, except that the PVA resin (A3) produced in Example of the Production Process 3 was used as the PVA resin (A), and the alcohol (D) and the surfactant (E) were not blended, and that the respective components were blended in proportions as shown in Table 2.
• the coating liquid for phosphorus diffusion was evaluated in the same manner as in Example 1. The viscosity of the coating liquid is shown in Table 2, and the evaluation results are shown in Table 3.
• the semiconductor substrate After the semiconductor substrate, on which the inventive coating liquid for boron diffusion was screen-printed, was dried at 150°C for 2 minutes in a hot air circulation drier, the semiconductor substrate was put in a muffle furnace at 950°C, maintained for 15 minutes, and taken out. Then, the substrate was shaken and cleaned in a 46% hydrogen fluoride aqueous solution. Thus, a semiconductor including a boron diffusion layer formed in the semiconductor substrate was produced.
• the surface resistance of the center of the resulting semiconductor with 30-mm square pattern was measured by means of a resistance meter (LORESTAR with a PSP probe available from Mitsubishi Analytech Co., Ltd.) The results are shown in Table 5.
• a coating liquid for boron diffusion was prepared in substantially the same manner as in Example 5, except that 54g of ultrapure water (C), 7g of the PVA resin (A3) produced in Example of the Production Process 3 as the PVA resin (A) and 35g of methyl carbitol as the alcohol (D) were used.
• the coating liquid for boron diffusion was evaluated in the same manner as in Example 5.
• the formulation and the viscosity of the coating liquid are shown in Table 4, and the evaluation results are shown in Table 5.
• a coating liquid for boron diffusion was prepared in substantially the same manner as in Example 5, except that 47.4g of ultrapure water (C), 13. 6g of an unmodified PVA (a2) (having a polymerization degree of 450 and a saponification degree of 87.5 mol%) as the PVA resin and 35g of methyl carbitol as the alcohol (D) were used.
• the coating liquid for boron diffusion was evaluated in the same manner as in Example 5. The formulation and the viscosity of the coating liquid are shown in Table 4, and the evaluation results are shown in Table 5.
• the printing properties were excellent during the screen printing even after the lapse of the predetermined periods.
• the coating liquid containing the PVA having a higher saponification degree was gelatinized, and the coating liquid containing the partially saponified PVA was properly prepared but suffered from pattern chipping when the printing was carried out after a lapse of 5 minutes.
• the semiconductors produced with the inventive coating liquid for boron diffusion each had a higher surface resistance.

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• 2011
  • 2011-11-29 CN CN2011800568283A patent/CN103229276A/zh active Pending
  • 2011-11-29 US US13/989,112 patent/US20130249059A1/en not_active Abandoned
  • 2011-11-29 EP EP11845216.8A patent/EP2648211A4/fr not_active Withdrawn
  • 2011-11-29 WO PCT/JP2011/077454 patent/WO2012073920A1/fr not_active Ceased
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